2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_INTRUSIVE_DETAILS_FELDMAN_HASHSET_BASE_H
32 #define CDSLIB_INTRUSIVE_DETAILS_FELDMAN_HASHSET_BASE_H
34 #include <memory.h> // memcmp, memcpy
35 #include <type_traits>
37 #include <cds/intrusive/details/base.h>
38 #include <cds/opt/compare.h>
39 #include <cds/algo/atomic.h>
40 #include <cds/algo/split_bitstring.h>
41 #include <cds/details/marked_ptr.h>
42 #include <cds/urcu/options.h>
44 namespace cds { namespace intrusive {
46 /// FeldmanHashSet related definitions
47 /** @ingroup cds_intrusive_helper
49 namespace feldman_hashset {
50 /// Hash accessor option
52 @copydetails traits::hash_accessor
54 template <typename Accessor>
55 struct hash_accessor {
57 template <typename Base> struct pack: public Base
59 typedef Accessor hash_accessor;
64 /// \p FeldmanHashSet internal statistics
65 template <typename EventCounter = cds::atomicity::event_counter>
67 typedef EventCounter event_counter ; ///< Event counter type
69 event_counter m_nInsertSuccess; ///< Number of success \p insert() operations
70 event_counter m_nInsertFailed; ///< Number of failed \p insert() operations
71 event_counter m_nInsertRetry; ///< Number of attempts to insert new item
72 event_counter m_nUpdateNew; ///< Number of new item inserted for \p update()
73 event_counter m_nUpdateExisting; ///< Number of existing item updates
74 event_counter m_nUpdateFailed; ///< Number of failed \p update() call
75 event_counter m_nUpdateRetry; ///< Number of attempts to update the item
76 event_counter m_nEraseSuccess; ///< Number of successful \p erase(), \p unlink(), \p extract() operations
77 event_counter m_nEraseFailed; ///< Number of failed \p erase(), \p unlink(), \p extract() operations
78 event_counter m_nEraseRetry; ///< Number of attempts to \p erase() an item
79 event_counter m_nFindSuccess; ///< Number of successful \p find() and \p get() operations
80 event_counter m_nFindFailed; ///< Number of failed \p find() and \p get() operations
82 event_counter m_nExpandNodeSuccess; ///< Number of succeeded attempts converting data node to array node
83 event_counter m_nExpandNodeFailed; ///< Number of failed attempts converting data node to array node
84 event_counter m_nSlotChanged; ///< Number of array node slot changing by other thread during an operation
85 event_counter m_nSlotConverting; ///< Number of events when we encounter a slot while it is converting to array node
87 event_counter m_nArrayNodeCount; ///< Number of array nodes
88 event_counter m_nHeight; ///< Current height of the tree
91 void onInsertSuccess() { ++m_nInsertSuccess; }
92 void onInsertFailed() { ++m_nInsertFailed; }
93 void onInsertRetry() { ++m_nInsertRetry; }
94 void onUpdateNew() { ++m_nUpdateNew; }
95 void onUpdateExisting() { ++m_nUpdateExisting; }
96 void onUpdateFailed() { ++m_nUpdateFailed; }
97 void onUpdateRetry() { ++m_nUpdateRetry; }
98 void onEraseSuccess() { ++m_nEraseSuccess; }
99 void onEraseFailed() { ++m_nEraseFailed; }
100 void onEraseRetry() { ++m_nEraseRetry; }
101 void onFindSuccess() { ++m_nFindSuccess; }
102 void onFindFailed() { ++m_nFindFailed; }
104 void onExpandNodeSuccess() { ++m_nExpandNodeSuccess; }
105 void onExpandNodeFailed() { ++m_nExpandNodeFailed; }
106 void onSlotChanged() { ++m_nSlotChanged; }
107 void onSlotConverting() { ++m_nSlotConverting; }
108 void onArrayNodeCreated() { ++m_nArrayNodeCount; }
109 void height( size_t h ) { if (m_nHeight < h ) m_nHeight = h; }
113 /// \p FeldmanHashSet empty internal statistics
116 void onInsertSuccess() const {}
117 void onInsertFailed() const {}
118 void onInsertRetry() const {}
119 void onUpdateNew() const {}
120 void onUpdateExisting() const {}
121 void onUpdateFailed() const {}
122 void onUpdateRetry() const {}
123 void onEraseSuccess() const {}
124 void onEraseFailed() const {}
125 void onEraseRetry() const {}
126 void onFindSuccess() const {}
127 void onFindFailed() const {}
129 void onExpandNodeSuccess() const {}
130 void onExpandNodeFailed() const {}
131 void onSlotChanged() const {}
132 void onSlotConverting() const {}
133 void onArrayNodeCreated() const {}
134 void height(size_t) const {}
138 /// \p FeldmanHashSet traits
141 /// Mandatory functor to get hash value from data node
143 It is most-important feature of \p FeldmanHashSet.
144 That functor must return a reference to fixed-sized hash value of data node.
145 The return value of that functor specifies the type of hash value.
149 typedef uint8_t hash_type[32]; // 256-bit hash type
151 hash_type hash; // 256-bit hash value
156 struct foo_hash_accessor {
157 hash_type const& operator()( foo const& d ) const
164 typedef cds::opt::none hash_accessor;
166 /// Disposer for removing data nodes
167 typedef cds::intrusive::opt::v::empty_disposer disposer;
169 /// Hash comparing functor
171 No default functor is provided.
172 If the option is not specified, the \p less option is used.
174 typedef cds::opt::none compare;
176 /// Specifies binary predicate used for hash compare.
178 If \p %less and \p %compare are not specified, \p memcmp() -like @ref bitwise_compare "bit-wise hash comparator" is used
179 because the hash value is treated as fixed-sized bit-string.
181 typedef cds::opt::none less;
185 The item counting is an important part of \p FeldmanHashSet algorithm:
186 the \p empty() member function depends on correct item counting.
187 Therefore, \p atomicity::empty_item_counter is not allowed as a type of the option.
189 Default is \p atomicity::item_counter.
191 typedef cds::atomicity::item_counter item_counter;
193 /// Array node allocator
195 Allocator for array nodes. That allocator is used for creating \p headNode and \p arrayNode when the set grows.
196 Default is \ref CDS_DEFAULT_ALLOCATOR
198 typedef CDS_DEFAULT_ALLOCATOR node_allocator;
200 /// C++ memory ordering model
202 Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
203 or \p opt::v::sequential_consistent (sequentially consisnent memory model).
205 typedef cds::opt::v::relaxed_ordering memory_model;
207 /// Back-off strategy
208 typedef cds::backoff::Default back_off;
210 /// Internal statistics
212 By default, internal statistics is disabled (\p feldman_hashset::empty_stat).
213 Use \p feldman_hashset::stat to enable it.
215 typedef empty_stat stat;
217 /// RCU deadlock checking policy (only for \ref cds_intrusive_FeldmanHashSet_rcu "RCU-based FeldmanHashSet")
219 List of available policy see \p opt::rcu_check_deadlock
221 typedef cds::opt::v::rcu_throw_deadlock rcu_check_deadlock;
224 /// Metafunction converting option list to \p feldman_hashset::traits
226 Supported \p Options are:
227 - \p feldman_hashset::hash_accessor - mandatory option, hash accessor functor.
228 @copydetails traits::hash_accessor
229 - \p opt::node_allocator - array node allocator.
230 @copydetails traits::node_allocator
231 - \p opt::compare - hash comparison functor. No default functor is provided.
232 If the option is not specified, the \p opt::less is used.
233 - \p opt::less - specifies binary predicate used for hash comparison.
234 If the option is not specified, \p memcmp() -like bit-wise hash comparator is used
235 because the hash value is treated as fixed-sized bit-string.
236 - \p opt::back_off - back-off strategy used. If the option is not specified, the \p cds::backoff::Default is used.
237 - \p opt::disposer - the functor used for disposing removed data node. Default is \p opt::v::empty_disposer. Due the nature
238 of GC schema the disposer may be called asynchronously.
239 - \p opt::item_counter - the type of item counting feature.
240 The item counting is an important part of \p FeldmanHashSet algorithm:
241 the \p empty() member function depends on correct item counting.
242 Therefore, \p atomicity::empty_item_counter is not allowed as a type of the option.
243 Default is \p atomicity::item_counter.
244 - \p opt::memory_model - C++ memory ordering model. Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
245 or \p opt::v::sequential_consistent (sequentially consisnent memory model).
246 - \p opt::stat - internal statistics. By default, it is disabled (\p feldman_hashset::empty_stat).
247 To enable it use \p feldman_hashset::stat
248 - \p opt::rcu_check_deadlock - a deadlock checking policy for \ref cds_intrusive_FeldmanHashSet_rcu "RCU-based FeldmanHashSet"
249 Default is \p opt::v::rcu_throw_deadlock
251 template <typename... Options>
254 # ifdef CDS_DOXYGEN_INVOKED
255 typedef implementation_defined type ; ///< Metafunction result
257 typedef typename cds::opt::make_options<
258 typename cds::opt::find_type_traits< traits, Options... >::type
264 /// Bit-wise memcmp-based comparator for hash value \p T
265 template <typename T>
266 struct bitwise_compare
268 /// Compares \p lhs and \p rhs
271 - <tt> < 0</tt> if <tt>lhs < rhs</tt>
272 - <tt>0</tt> if <tt>lhs == rhs</tt>
273 - <tt> > 0</tt> if <tt>lhs > rhs</tt>
275 int operator()( T const& lhs, T const& rhs ) const
277 return memcmp( &lhs, &rhs, sizeof(T));
281 /// One-level statistics, see \p FeldmanHashSet::get_level_statistics
282 struct level_statistics
284 size_t array_node_count; ///< Count of array node at the level
285 size_t node_capacity; ///< Array capacity
287 size_t data_cell_count; ///< The number of data cells in all array node at this level
288 size_t array_cell_count; ///< The number of array cells in all array node at this level
289 size_t empty_cell_count; ///< The number of empty cells in all array node at this level
293 : array_node_count(0)
295 , array_cell_count(0)
296 , empty_cell_count(0)
303 template <typename HashType >
304 using hash_splitter = cds::algo::split_bitstring< HashType >;
307 size_t head_node_size; // power-of-two
308 size_t head_node_size_log; // log2( head_node_size )
309 size_t array_node_size; // power-of-two
310 size_t array_node_size_log;// log2( array_node_size )
312 static metrics make(size_t head_bits, size_t array_bits, size_t hash_size )
314 size_t const hash_bits = hash_size * 8;
320 if (head_bits > hash_bits)
321 head_bits = hash_bits;
322 if ((hash_bits - head_bits) % array_bits != 0)
323 head_bits += (hash_bits - head_bits) % array_bits;
325 assert((hash_bits - head_bits) % array_bits == 0);
328 m.head_node_size_log = head_bits;
329 m.head_node_size = size_t(1) << head_bits;
330 m.array_node_size_log = array_bits;
331 m.array_node_size = size_t(1) << array_bits;
336 } // namespace details
340 template <typename T, typename Traits>
341 class multilevel_array
344 typedef T value_type;
345 typedef Traits traits;
346 typedef typename Traits::node_allocator node_allocator;
347 typedef typename traits::memory_model memory_model;
348 typedef typename traits::back_off back_off; ///< Backoff strategy
349 typedef typename traits::stat stat; ///< Internal statistics type
351 typedef typename traits::hash_accessor hash_accessor;
352 static_assert(!std::is_same< hash_accessor, cds::opt::none >::value, "hash_accessor functor must be specified");
354 /// Hash type deduced from \p hash_accessor return type
355 typedef typename std::decay<
356 typename std::remove_reference<
357 decltype(hash_accessor()(std::declval<value_type>()))
360 static_assert(!std::is_pointer<hash_type>::value, "hash_accessor should return a reference to hash value");
362 typedef typename cds::opt::details::make_comparator_from<
365 feldman_hashset::bitwise_compare< hash_type >
366 >::type hash_comparator;
368 typedef feldman_hashset::details::hash_splitter< hash_type > hash_splitter;
371 flag_array_converting = 1, ///< the cell is converting from data node to an array node
372 flag_array_node = 2 ///< the cell is a pointer to an array node
377 typedef cds::details::marked_ptr< value_type, 3 > node_ptr;
378 typedef atomics::atomic< node_ptr > atomic_node_ptr;
381 array_node * const pParent; ///< parent array node
382 size_t const idxParent; ///< index in parent array node
383 atomic_node_ptr nodes[1]; ///< node array
385 array_node(array_node * parent, size_t idx)
390 array_node() = delete;
391 array_node(array_node const&) = delete;
392 array_node(array_node&&) = delete;
395 typedef cds::details::Allocator< array_node, node_allocator > cxx_array_node_allocator;
397 struct traverse_data {
398 hash_splitter splitter;
403 traverse_data( hash_type const& hash, multilevel_array& arr )
409 void reset( multilevel_array& arr )
413 nSlot = splitter.cut( arr.metrics().head_node_size_log );
419 feldman_hashset::details::metrics const m_Metrics;
424 multilevel_array(size_t head_bits, size_t array_bits )
425 : m_Metrics(feldman_hashset::details::metrics::make(head_bits, array_bits, sizeof(hash_type)))
426 , m_Head( alloc_head_node())
432 free_array_node(m_Head);
435 node_ptr traverse(traverse_data& pos)
439 node_ptr slot = pos.pArr->nodes[pos.nSlot].load(memory_model::memory_order_acquire);
440 if (slot.bits() == flag_array_node) {
441 // array node, go down the tree
442 assert(slot.ptr() != nullptr);
443 assert( !pos.splitter.eos());
444 pos.nSlot = pos.splitter.cut( metrics().array_node_size_log );
445 assert( pos.nSlot < metrics().array_node_size );
446 pos.pArr = to_array(slot.ptr());
449 else if (slot.bits() == flag_array_converting) {
450 // the slot is converting to array node right now
452 stats().onSlotConverting();
456 assert(slot.bits() == 0);
462 size_t head_size() const
464 return m_Metrics.head_node_size;
467 size_t array_node_size() const
469 return m_Metrics.array_node_size;
472 void get_level_statistics(std::vector< feldman_hashset::level_statistics>& stat) const
475 gather_level_statistics(stat, 0, m_Head, head_size());
479 array_node * head() const
489 feldman_hashset::details::metrics const& metrics() const
496 // The function is not thread-safe. For use in dtor only
497 // Destroy all array nodes
498 destroy_array_nodes(m_Head, head_size());
501 void destroy_array_nodes(array_node * pArr, size_t nSize)
503 for (atomic_node_ptr * p = pArr->nodes, *pLast = p + nSize; p != pLast; ++p) {
504 node_ptr slot = p->load(memory_model::memory_order_relaxed);
505 if (slot.bits() == flag_array_node) {
506 destroy_array_nodes(to_array(slot.ptr()), array_node_size());
507 free_array_node(to_array(slot.ptr()));
508 p->store(node_ptr(), memory_model::memory_order_relaxed);
513 static array_node * alloc_array_node(size_t nSize, array_node * pParent, size_t idxParent)
515 array_node * pNode = cxx_array_node_allocator().NewBlock(sizeof(array_node) + sizeof(atomic_node_ptr) * (nSize - 1), pParent, idxParent);
516 new (pNode->nodes) atomic_node_ptr[nSize];
520 array_node * alloc_head_node() const
522 return alloc_array_node(head_size(), nullptr, 0);
525 array_node * alloc_array_node(array_node * pParent, size_t idxParent) const
527 return alloc_array_node(array_node_size(), pParent, idxParent);
530 static void free_array_node(array_node * parr)
532 cxx_array_node_allocator().Delete(parr);
539 converter(value_type * p)
543 converter(array_node * p)
548 static array_node * to_array(value_type * p)
550 return converter(p).pArr;
552 static value_type * to_node(array_node * p)
554 return converter(p).pData;
557 void gather_level_statistics(std::vector<feldman_hashset::level_statistics>& stat, size_t nLevel, array_node * pArr, size_t nSize) const
559 if (stat.size() <= nLevel) {
560 stat.resize(nLevel + 1);
561 stat[nLevel].node_capacity = nSize;
564 ++stat[nLevel].array_node_count;
565 for (atomic_node_ptr * p = pArr->nodes, *pLast = p + nSize; p != pLast; ++p) {
566 node_ptr slot = p->load(memory_model::memory_order_relaxed);
568 ++stat[nLevel].array_cell_count;
569 if (slot.bits() == flag_array_node)
570 gather_level_statistics(stat, nLevel + 1, to_array(slot.ptr()), array_node_size());
573 ++stat[nLevel].data_cell_count;
575 ++stat[nLevel].empty_cell_count;
579 bool expand_slot( traverse_data& pos, node_ptr current)
581 return expand_slot( pos.pArr, pos.nSlot, current, pos.splitter.bit_offset());
585 bool expand_slot(array_node * pParent, size_t idxParent, node_ptr current, size_t nOffset)
587 assert(current.bits() == 0);
588 assert(current.ptr());
590 array_node * pArr = alloc_array_node(pParent, idxParent);
592 node_ptr cur(current.ptr());
593 atomic_node_ptr& slot = pParent->nodes[idxParent];
594 if (!slot.compare_exchange_strong(cur, cur | flag_array_converting, memory_model::memory_order_release, atomics::memory_order_relaxed))
596 stats().onExpandNodeFailed();
597 free_array_node(pArr);
601 size_t idx = hash_splitter( hash_accessor()(*current.ptr()), nOffset ).cut( m_Metrics.array_node_size_log );
602 pArr->nodes[idx].store(current, memory_model::memory_order_release);
604 cur = cur | flag_array_converting;
606 slot.compare_exchange_strong(cur, node_ptr(to_node(pArr), flag_array_node), memory_model::memory_order_release, atomics::memory_order_relaxed)
609 stats().onExpandNodeSuccess();
610 stats().onArrayNodeCreated();
615 } // namespace feldman_hashset
618 // Forward declaration
619 template < class GC, typename T, class Traits = feldman_hashset::traits >
620 class FeldmanHashSet;
623 }} // namespace cds::intrusive
625 #endif // #ifndef CDSLIB_INTRUSIVE_DETAILS_FELDMAN_HASHSET_BASE_H